Revegetation of degraded soils is crucial to prevent erosion and improve soil structure and quality. We aimed to elucidate the role of the root system of grasses on the reclamation of a soil constructed after coal mining. In Candiota city, in Brazil, perennial grasses (Hemarthria, Paspalum, Cynodon, and Brizantha) were cultivated for 103 months, when soil samples were collected from 0.00–0.30 m layer. The root development of these species substantially decreased in depth, reflecting soil restrictive conditions, as high soil penetration resistance, especially below 0.10 m, assigned to the use of heavy machinery during soil construction. Below 0.10 m depth, fine and flattened roots were observed, which penetrated through the cracks of compacted soil layers. Regardless of the soil layer, all plant species had a greater proportion of roots <0.49 than >0.50 mm diameter class, averaged 92 and 8%, respectively. Below 0.10 m depth, Brizantha increased the proportion of roots >0.50 mm diameter class, while the other grasses increased the proportion of roots <0.49 mm diameter class. The highest root density, volume, and length observed for Brizantha along the soil profile indicate its high potential to improve physical attributes and therefore the quality of the constructed soil.
Part of the book: Grasses as Food and Feed
The largest Brazilian coal mine, called Candiota mine, is located in South Brazil, with an estimated reserve about 1.2 billion tons. Since late 2003, an experiment located at a reclaimed site in a coal mining area was conducted, in which a research group from the Federal University of Pelotas has been conducting a long-term experiment on soil quality with different plants species, such as Hemarthria altissima, Paspalum notatum cv. Pensacola, Cynodon dactylon cv. Tifton, and Urochloa brizantha. After 8.6 years of revegetation, soil samples at 0.20 depth were collected in minesoil and natural soil to determine physical attributes, and the organic carbon content. After 10.9 years of revegetation, soil samples at 0.10 m depth were collected to determine the biological attributes. According to the research results, it can be seen that the recovery of minesoil was more effective after 8.6 years of revegetation only in the physical condition up to 0.10 m depth. However, all soil physical attributes and organic matter content are still below the levels observed in the natural soil. The biological attributes after 10.9 years of revegetation have not yet been sufficient to restore a mites and springtails population close to the natural soil.
Part of the book: Mining Techniques